As an example of such flange coupling part reinforcing jig as described above, Patent Document 1, for instance, discloses an arrangement where at portions of the two clamping members opposed to each other in the flange coupling direction, there are formed a pair of bolt threading holes (an example of “fastening means”) formed at positions more radially outward than the outer circumference faces of the two flange parts, and two threading bolts (an example of “fastening means”) are threaded to and between the pair of bolt threading holes, with pressing parts formed at positions of the two clamping members more radially inward than the bolt threading holes being placed in abutment with the outer faces of the two flange parts.
Further, as another example of such flange coupling part reinforcing jig as described above, Patent Document 2, for instance, discloses a following arrangement. Namely, one of the two clamping members is provided in form of an approximately angular hook-shaped member (approximately U-shaped member) having a pair of leg portions, the other of the two clamping members is provided in form of a bolt (as example of “fastening means”) which is threadingly fitted to one of the pair of leg portions. The leading end of the bolt and an inner circumferential face of the other leg portion of the angular hook-shaped member to which the bolt is not attached are provided as pressing parts for pressing outer faces of the two flange parts respectively. And, as the bolt is threaded to the one leg portion and further fastened, the leading end of the bolt and the inner circumferential face of the other leg portion are placed in abutment with the outer faces of the flange portions respectively, and the flange parts are fastened and fixed by the pair of clamping members (the angular hook-shaped member (U-shaped members and the bolt).
It is said that by fastening and fixing the pair of clamping members by the fastening means with use of such flange coupling part reinforcing jigs described above, there can be realized coupling reinforcement of the two flange parts by a plurality of bolts/nuts as well as increased fastening strength by the fastening means, consequently, inadvertent separation of the two flange parts can be prevented even in the event of application of a force in the bending or pulling direction to the two flange parts, so that gas-tightness can be maintained.